What Is Azure Private Link And How To Deploy With Terraform

Azure Private Link offers several benefits, including enhanced security, simplified network architecture, and improved performance. It supports various Azure services like Azure Storage and Azure SQL Database, allowing organizations to maintain the privacy and integrity of their data. Moreover, Azure Private Link seamlessly integrates with Azure Virtual Networks (VNets), on-premises networks and supports global connectivity, making it a versatile solution for enterprises with diverse and distributed infrastructure.

This article explains what Azure Private Link is, exploring its components, benefits, and deployment strategies. The article also explains the steps to configuring Azure Storage Account security using Azure Private Link with HashiCorp Terraform infrastructure as code (IaC). By the end of this article, you will have a comprehensive understanding of Azure Private Link and be equipped with the knowledge to deploy it effectively using Terraform in your own cloud environments.

What is Azure Private Link?

Azure Private Link is a critical service for organizations that prioritize security and privacy in their cloud deployments. By providing a private endpoint in a virtual network, Azure Private Link ensures that your data stays within the Azure backbone network, reducing exposure to the public internet.

When a private endpoint is created, it is assigned an IP address from the virtual network subnet. This endpoint is mapped to the Azure service resource, allowing you to access the service privately. Azure Private Link provides a secure, scalable method to connect to services such as Azure Storage, Azure SQL Database, and custom services, maintaining the privacy and integrity of your data.

Azure Private Link supports the use of Network Security Groups (NSGs), User Defined Routes (UDRs), and Application Security Groups (ASGs) to enforce network policies on private endpoints. This allows you to control and restrict traffic flow, enhancing security further.

By configuring NSGs, you can define rules to permit or deny traffic to your private endpoints. This granular control helps protect your resources from unauthorized access and potential threats.

Connecting to a private link service can be managed through an approval workflow. This can be either automatic or manual, depending on the permissions and configurations. When a connection request is initiated, it enters a pending state until approved by the service owner, ensuring that only authorized connections are established.

Let’s look at each of the components, benefits, and key functionalities.

Key Components of Azure Private Link

1. Private Endpoint: A private endpoint is a network interface that connects you privately to a service powered by Azure Private Link. It brings the service into your virtual network, enabling you to access it as if it were part of your local network. This connection is established using a private IP address from your virtual network, thereby eliminating the need for a public IP address.
2. Private Link Service: The private link service is a service configured for private connectivity. It could be an Azure PaaS service, a Microsoft partner service, or your own service. When you configure a private link service, a network interface is created, which facilitates the private connectivity.
3. DNS Integration: Azure Private Link seamlessly integrates with Azure DNS to provide private DNS resolution for the connected services. This ensures that services accessed via private endpoints are resolvable within your virtual network using custom domain names, maintaining the simplicity and familiarity of DNS while enhancing security.

Benefits of Azure Private Link

1. Enhanced Security: By eliminating the need for data to traverse the public internet, Azure Private Link provides robust protection against data exfiltration. Only authorized services can communicate with each other, reducing the risk of unauthorized access and potential data breaches.
2. Simplified Network Architecture: Azure Private Link simplifies network architecture by removing the necessity for public IP addresses, NAT devices, or gateways to communicate with Azure services. The private endpoint makes Azure services accessible as if they are part of your own network, streamlining network management and configuration.
3. Improved Performance: Private connectivity through Azure Private Link reduces latency and improves performance. Since the traffic does not traverse the public internet, data transfer rates are faster and more consistent, enhancing the overall user experience.
4. Global Reach: Private Link allows for global connectivity. Services can be accessed privately across different Azure regions, making it easier to deploy multi-region solutions without exposing data to the public internet. This is particularly useful for global enterprises needing consistent and secure access to services across various geographic locations.
5. Integration with On-Premises Networks: Azure Private Link can be extended to on-premises environments via VPN or ExpressRoute. This ensures that even on-premises applications can securely interact with Azure services, maintaining a consistent security posture across hybrid cloud environments.

Use Cases for Azure Private Link

Azure Private Link is particularly beneficial for scenarios requiring secure and private access to Azure services.

These are several potential use cases:

• Secure Data Access: Private Link is ideal for accessing Azure PaaS services like Azure Storage, SQL Database, and Azure Kubernetes Service securely from your virtual network. It ensures that your data remains within the secure confines of the Azure backbone network, reducing exposure to the public internet.
• Service Providers: For service providers hosting their applications on Azure, Private Link enables the delivery of these applications to customers’ virtual networks privately. Customers can connect to these applications using private endpoints, enhancing security and privacy for end users.
• Cross-Region Solutions: Azure Private Link supports scenarios where services and customers are in different regions. This is useful for applications requiring high availability and disaster recovery, allowing seamless failover and connectivity across regions without compromising security.

Practical Considerations and Best Practices

When deploying Azure Private Link, it’s crucial to consider network policies and security configurations to ensure that only authorized traffic can access your private endpoints. Leveraging tools like Azure Monitor and Network Watcher can help in monitoring and maintaining the health of your network connections.

Here are several best practices to keep in mind when using Azure Private Link:

• Plan for Redundancy: To ensure high availability, deploy private endpoints across multiple regions and availability zones. This provides resilience against regional outages and maintains service continuity.
• Use Appropriate Subnets: While dedicated subnets for private endpoints are not required, carefully choose subnets to avoid IP address conflicts and ensure optimal network performance.
• Regularly Review Access Controls: Periodically review and update access controls to ensure that only authorized users and services have access to your private endpoints. This helps maintain a strong security posture and reduces the risk of unauthorized access.
• Understand Cost Implications: Be aware of the costs associated with private endpoints, including data transfer and endpoint hourly rates. Plan your deployment to optimize costs while meeting your security and performance requirements.

Azure Private Link is a powerful tool for securing and simplifying the connectivity between your virtual network and Azure services. By using private endpoints and maintaining traffic within the Microsoft backbone network, it offers enhanced security, streamlined network management, and global connectivity, making it an essential component for modern cloud architectures.

Deploying Azure Private Link with HashiCorp Terraform

Let’s take a look at configuring Azure Private Link to secure access to an Azure Storage Account using HashiCorp Terraform. This is a common task performed, and this example should help you configure Private Link for any other Azure Resources you need to secure.

Follow these steps to set up Azure Private Link to secure access to an Azure Storage Account using HashiCorp Terraform:

Step 1: Create Virtual Network and Subnet

Azure Private Link enables the secure connectivity of a PaaS service with an Azure Virtual Network. This will first require that you have a Virtual Network (VNet) and Subnet configured for the Azure Private Link to connect to.

Here’s an example of configuring these, in addition to a resource group to place everything in:

resource azurerm_resource_group "b59_rg" {
  name     = "eus-b59-rg"
  location = "eastus"
}

resource azurerm_virtual_network "b59_vnet" {
  name                = "eus-b59-vnet"
  address_space       = ["10.0.0.0/16"]
  location            = azurerm_resource_group.b59_rg.location
  resource_group_name = azurerm_resource_group.b59_rg.name
}

resource azurerm_subnet "b59_ple_subnet" {
  name                 = "ple"
  resource_group_name  = azurerm_resource_group.b59_rg.name
  virtual_network_name = azurerm_virtual_network.b59_vnet.name
  address_prefixes     = ["10.0.1.0/24"]

  service_endpoints = ["Microsoft.Storage"]
}

As you can see, I named the subnet ple since it will be used for connecting Private Link Endpoints. You will want to create a separate subnet for Private Link to use form the Subnets you create for other Azure resources that connect to the VNet, like Virtual Machines (VMs) or VNet integrated resources.

This is also configuring the Service Endpoints (via service_endpoints argument) on the Subnet to support Service Endpoint connections with Azure Storage Accounts.

Step 2: Create Azure Storage Account

To securely connect an Azure Storage Account using Azure Private Link, we’ll definitely need a Storage Account.

Here’s an example storage account:

resource azurerm_storage_account "b59_sa" {
  name                     = "eusb59sa"
  resource_group_name      = azurerm_resource_group.b59_rg.name
  location                 = azurerm_resource_group.b59_rg.location
  account_tier             = "Standard"
  account_replication_type = "LRS"

  network_rules {
    default_action             = "Deny"
    virtual_network_subnet_ids = [azurerm_subnet.b59_ple_subnet.id]
    bypass                     = ["None"]
    ip_rules                   = []
  }
}

The network_rules is configured to allow connections to the Storage Account from the ple Subnet, and to disable connectivity from both the public Internet and “trusted” Azure Services.

Step 3: Create Azure Private Endpoint

resource azurerm_private_endpoint "b59_sa_ple_blob" {
  name                = "eus-b59-sa-ple"
  location            = azurerm_resource_group.b59_rg.location
  resource_group_name = azurerm_resource_group.b59_rg.name
  subnet_id           = azurerm_subnet.b59_ple_subnet.id

  private_service_connection {
    name                           = "eus-b59-sa-privatelink-connection"
    private_connection_resource_id = azurerm_storage_account.b59_sa.id
    subresource_names              = ["blob"]
    is_manual_connection           = false
  }
}

This block creates a private endpoint, which connects your virtual network privately and securely to the storage account. The private_service_connection block within it specifies the connection details, including the resource ID of the Azure Storage Account and the sub-resource (e.g., blob for Blob storage) via the subresource_names parameter.

The subresource_names parameter in the Terraform configuration for Azure Private Endpoint specifies which sub-resource of the Azure service you are connecting to via the private endpoint. This is necessary because some Azure services have multiple sub-resources that can be accessed, each potentially requiring a separate private endpoint.

For Azure Storage Accounts, these are the options for the sub-resources to configure:

• blob for accessing the Blob storage endpoint of the Storage Account.
• file for accessing the Azure Files endpoint of the Storage Account.
• queue for accessing the Queue storage endpoint for the Storage Account.
• table for accessing the Azure Tables endpoint of the Storage Account.

Keep in mind that other resources (like: Azure SQL Database, Key Vault, or Cosmos DB) have different subresource_names to be configured when configuring Private Endpoints for those services.

Step 4: Create Private DNS Zone

When setting up a private endpoint for Azure Blob Storage, configuring a private DNS zone is not strictly required, but it is highly recommended. This configuration facilitates seamless connectivity by ensuring that the storage account’s fully qualified domain name (FQDN) resolves to the private IP address of the private endpoint within your virtual network.

resource "azurerm_private_dns_zone" "b59_private_sa_dns_zone" {
  name                = "privatelink.blob.core.windows.net"
  resource_group_name = azurerm_resource_group.b59_rg.name
}

resource "azurerm_private_dns_zone_virtual_network_link" "b59_vnet_link" {
  name                  = "b59-vnet-link"
  resource_group_name   = azurerm_resource_group.b59_rg.name
  private_dns_zone_name = azurerm_private_dns_zone.b59_private_sa_dns_zone.name
  virtual_network_id    = azurerm_virtual_network.b59_vnet.id
}

resource "azurerm_private_dns_a_record" "example" {
  name                = azurerm_storage_account.b59_sa.name
  zone_name           = azurerm_private_dns_zone.b59_private_sa_dns_zone.name
  resource_group_name = azurerm_resource_group.b59_rg.name
  ttl                 = 300
  records             = [azurerm_private_endpoint.b59_sa_ple_blob.private_service_connection[0].private_ip_address]
}

These resources configure a private DNS zone and link it to the virtual network. The azurerm_private_dns_a_record resource creates a DNS A record pointing to the private endpoint’s IP address, enabling DNS resolution within the virtual network.

Conclusion

Azure Private Link provides a robust solution for secure and private access to Azure services. By using Terraform, you can automate and streamline the deployment process, ensuring consistent and repeatable infrastructure setups. This combination of tools enhances security and operational efficiency, enabling you to focus more on application development and less on managing infrastructure.

By adhering to the best practices and detailed steps outlined above, you can confidently deploy Azure Private Link in your environment, leveraging the power of Terraform to automate and manage your cloud infrastructure effectively.

Original Article Source: What is Azure Private Link and How to Deploy with Terraform by Chris Pietschmann (If you’re reading this somewhere other than Build5Nines.com, it was republished without permission.)